1. Field of the Invention
The present invention relates to toner compositions for electrostatic developing. More particularly, this invention relates to toner compositions with good release properties, and with charging characteristics that are very stable with respect to temperature and humidity.
2. Background Information
Toner compositions for electrostatic developing (ED) processes typically contain at least one thermoplastic resin and a colorant as principal ingredients together with various optional additives, for example, charging regulators, fluidizers, fillers, and cleaners. The homogeneity, charging properties, fluidity, fusing characteristics, and other properties of these ED toner can be regulated or adjusted by selecting particular combinations of these ingredients.
One problem with prior art ED toners is the variation of their charging properties with temperature and humidity. These toners do not release well from hot-fixing rolls, and as a result stain the surface of such rolls. In addition, the heavy metal-based organometallic compounds heretofore used as charging regulators are colored and toxic. As a consequence, the resulting ED toner is toxic to humans and contaminates the environment, and, in the case of color copiers, suffers from a degraded color tone.
One objective of the present invention is to provide a releasable ED toner whose charging properties are very stable with respect to temperature and humidity. A second objective of this invention is to the introduction of a releasable ED toner containing a white charging regulator comprising an organosiloxane resin.